John Johnson Nop Hop Reduction Gear Box Setup Measurements

[joescoolcustoms]

I had posted up in my thread about building a Oval Baja with a early split bus RGB (Reduction Gear Box) rear suspension using the John Johnson No Hop kit that I would post up the kit dimensions.

Here is a link to my build. I am done with the suspension, but not the body as I write this thread. So I have yet to test them, but many people have messaged me asking for the JJ Ho Hop dimensions.
http://www.thesamba.com/vw/forum/viewtopic.php?t=421262
Even though I have not completly finished the Oval baja at this date, it is a good thread on how to install the RGB in a Type 1 baja/buggy.


In my hunt for a JJ No Hop kit, I came across two NOS (New Old Stock) kits that had not been used. Both were JJ manufactured kits, but they varied in some dimensions.

Varations in dimensions

The lower strut bar varied in center to center length by 3/4 inch. The plate thickness varied from 1/4 inch thick to 5/16 thick. The forward strut bar mount varied how much it stood off the torsion tube by 3/8 inch.

These kits are not rocket science to build and do not have to be dead on to work. They just have to match side to side and be made of good quality parts. So, you can build the lower strut bar out of boxed tubing, rectangle tubing or round tubing. You can use urathene sleeved ends, uni-balls, solid mounts (will transmit vibrations/noise and wear quickly), rubber sleeved ends or hiem joints. Just use quality parts and good construction for your safety.

Basics on how the JJ No Hop Kit Works

The axle on a RGB transaxle rotates backwards compared to a Type 1 transaxle axle so it can drive a smaller top straight cut gear that drives a lower larger gear. This reverse rotation and two gear stack on the end of the swing axle tube returns the lower stub axle to a standard forward rotation. The smaller drive gear compared to the larger driven gear affords a gear reduction at the wheel. This reduction of either 1.36: 1 or 1.26:1 (there is another rare mountian ratio that was used in Germany, but not imported for sale in the US) gives a torque multiplier that helps make creaping over rocks, hurdles, and climbing steep grades much easier.

Because the top gear rotates backwards, under power, it tends to want to climb around the lower stub axle gear. This action will produce a wheel hop that can drop the filings out of your wisdom teeth that you had pulled when you were young. It can get so violent with big horse power pushing it that it can split a transmission case, bend the transmission cradle forks, break the gear stack, warp spring plates, separate header tubes, disconect wiring, loose your glasses off of your nose and other bad stuff.

Here is a transaxle that suffered badly under too much power and a bad case of hopping. Note how the ring gear is on the passenger side of the pinion to make the axles rotate backwards.

This brings the question, "how to stop the hop". Since the stock setup tries to wrap up the spring plate and climb the gears over one another, the force of the "push" the lower stub axle gives has to be re-focused to the chassis. The spring plate has to be disconnected from the axle tube end and allowed to pivot. This will allow the spring plate to just act as the suspension spring and hold the car up off of the ground, but not locate the axle and "push" the car forward. The alxe tube pivot is a close fit over the stock axle tube and has a grease zerk fitting because the axle tube piviots inside this flanged over tube. The pivot tube bolts to the spring plate and allows the axle tube to rotate inside of it.

Now, since the axle tube can rotate freely inside the tube pivot, it has to be fastened to the chassis with the lower strut bar. This strut bar focuses the push of the power from the tranny to the chassis. Focusing the power transition down low takes away the tendency to hop.

No Hop Dimensions

The strut bar I have measures 12 1/2 inches center pivot hole to center pivot hole. The strut bar measures 2 inch X 1 inch rectangle tubing with sleeved urathene bushings on the ends. The width of the sleeve in the bushing is 1.550 inches. This is also how far apart the rear pivot and the front pivot mounts are to accept the strut bar in and slide a 1/2 inch bolt through.

The front strut bar mount is stepped off the torsion tube 2 1/4 inch. These front mounts use a slightly different outside mount than the inside mounts to account for the inward angle that the bar is installed on.

The strut bar is located 7* angle from the spring plate. The reason is if it ran parrallel to the spring plate, it would hit the bottom of the spring plate. It is angled inward to bring the front pivot mount inboard just enough to clear the bottom of the torsion tube ends and weld to the torsion tube.

The rear lower mount is kind of self explained in the photo's. It is hard to give a measurement other than it has to pick up the four bolt holes and cant 7* inward to point the bar inboard of the torsion tube ends. It also picks up the lower shock mount.

As I stated early in this thread, these kits are not hard to make, just make a mirror image for the other side. The lower strut bar can be another inch longer and still be fine. The rear bottom mount can be slightly lower to accomodate a longer shock if desired.
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[Ian]

Awesome write up!! thank you for taking so much time to put this together!!!!!!!!!!
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[ryedizzle]

holy crap. i now understand these things! great write up!

[mopargraveyard]

Thanks for the great pictures and info. I'm taking my boxes to work today to clean them up .

[colorado_aircooled]

Thanks for the write up and saving a part of VW history at the same time. John Johnson was not only a GREAT offroad racer but also tackled the Pikes Peak Hill Climb. Curious how many of these kits were made, had to be hard to find just one set, let alone TWO ! Good Job !

[George Reeps]

Johnny Johnson No-Hop Reduction Gear Box, Rear Suspension Kit, 4-Sale $400 obo

I have this kit for sale $400 obo. I used it my 1957 Baja Truck that had a large nut 1966 Bus swing axle with 3.88 R&P… I loved this kit! It gave me a strong mounting system that works like a four link rear end. Raised my Baja 3-1/2 inches and kept the tires level/flat on the road. Recently I sold the Baja that I’ve owned since 1979 but kept the Johnny no-hop kit.

Link to photos
http://www.thesamba.com/vw/classifieds/detail.php?id=1321607

[hotrodsurplus]

[George Reeps]

I drove my "TRUG" Truck/Bug from 1978-1986 and have parked it in my barn ever since. It was my daily driver with a 1835cc, I used street tires that were 50x15 and they road nicely; no camber wear. I just pulled the transaxle to install it into my 1961 double cab and then sold my TRUG. I sent the transaxle to a VW Shop called Crossroads in Stockton, CA. to have it completely gone through. All the internals checked out ok. The outer tubes were polished from use/wear but there was no significant damage.

The photos posted in the above link showing the tubes… These tubes look shorter compared to mine. Mine are 10” long, with 3 zirks, and my struts came out of a early corvette.

I did see an unexpected wear pattern from the zerks being too long, as they protruded pass the Johnny tubing. I would suggest you weld a small nut on the outer part of the Johnny tube where the existing zirks screw in; then drill them to except new zerks. Also you should take a rotary file and grind down the ID area around the zirks to make them smooth.

With that said: I would expect that yours will last 20+ years with no sighs of damage.

Link to photos
http://www.thesamba.com/vw/classifieds/detail.php?id=1321607

[manasteel]

How thick is the tube that is used for the pivot?
How thick is flange that is welded to the tube?
I bought some 2" x .095 wall DOM tube, the fit is perfect but im wondering if it might be on the thin side.

[George Reeps]

I've sold my kit.
Flanges were 3/16"
Tubing 1/8" .125
You could use what you have, If you add some 1/8 gussets.
Try using three each, per side; 1-1/4 inch by 4 inch triangle gussets.


My 1961 DC project
http://www.thesamba.com/vw//forum/album_search.php...1f0fe03f97

[dcamomanx]

The bushings on my lower arms were worn. After removing the worn bushing I was able to find some replacements. They fit perfect

Here's the link

http://www.energysuspensionparts.com/proddetail.asp?prod=19906#

Hope that helps

Doran

[jackwyse]

I would sure like to find one of these kits does anyone know where I can find
One for my project

[Will6]

I too would love to find one of these kits, or the dimensions to make one myself. Any info would be greatly appreciated.

Need it in the snow up here in Canada...

Thanks
Will
[email protected]
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Keep the Beetle Heart Beating...VWCPR

[joescoolcustoms]

I have plenty of photo's and the corresponding dimensions listed above. A fabricator can use that information and the RGB box to make a set.
_________________
Bad News Racing 2018 NORRA 1000 3rd in Class
Best Day Ever Racing 2022 NORRA 1000 2nd in Class and first All Female team to complete the race

Everyone is gifted. Some just do not open the package.

Looks like it was painted with a live chicken,polished with a brick and buffed with a pine cone

[AlteWagen]

I thought the struts in the last kits were from corvettes, might be easier to find a set in the junk yard if you cant fab too much.

Any info on a 'lay down' kit?
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[Bashr52]

What is the purpose of the additional tube over the axle tube? It doesn't appear to tied into anything else associated with the No-hop kit?

[oldschool5er]

[joescoolcustoms]

The sleeves are not tube stiffeners. They are the pivots to allow the RGB to rotate instead of bind up. The Spring Plate bolts to the pivot tube and the RGB spins freely inside of it, that is the reason for the zero grease fittings.
_________________
Bad News Racing 2018 NORRA 1000 3rd in Class
Best Day Ever Racing 2022 NORRA 1000 2nd in Class and first All Female team to complete the race

Everyone is gifted. Some just do not open the package.

Looks like it was painted with a live chicken,polished with a brick and buffed with a pine cone

[dustymojave]

My Hi Jumper in my avatar has always had axle tube stiffeners without RGBs.

But yes, in a Johnny Johnson No-Hop kit, the axle sleeves ARE pivot tubes. The regular axle tube rides inside of the sleeve to rotate (I think that's a more fitting word than "spins") and thus let the 2nd link take up torque thrust to eliminate "hop" as one reduction gear tries to climb the other when power is applied.
_________________
Richard
Offroading VW based cars since 1965
Tech Inspection 1963 - 2012 SCCA/SCORE/HDRA/MORE/MDR +
Retired from building Bajas, Fiberglass Buggies and Rails in the Mojave Desert. Also Sprints & Midgets, Dry Lakes, Road Race cars. All types New and Vintage
SoCalBajas Member
Kicked Cancer's A$$...1st and 2nd round...Fight ain't over yet.

[Bashr52]